The present invention relates generally to grain drying and storing and more particularly to an apparatus for achieving proper ventilation of grain in a grain bin during the drying and storing process.
When grain is dried in a grain bin by circulating air through the grain, a crust tends to form in the grain, especially on the top layer thereof, because of an accumulation of moisture. It has been found that if the exhaust pressure of the air in a drying grain bin is maintained under a higher pressure, that this condition will tend to retain more moisture in the air than if it were under a lower pressure, and consequently that this moisture can be kept in the air until it is received into the atmosphere, at which time the moisture is then free to condense without depositing this moisture on the top layers of the grain. It has therefore been a problem of how to regulate the pressure in order to achieve this desired result.
Grain bins normally have an access opening at the top thereof. This opening is used for example to introduce the grain into the bin initially. This access opening normally has a door associated therewith. This door would, of course, be open when grain is being introduced into the bin and it would also be open during the drying process. During both the drying and the storing processes, this door would need to be manually or otherwise closed during rainy or snowy weather conditions in order to prevent moisture from entering the bin. Consequently, it can be clearly understood that there is a monitering problem with the use of a door. Someone must always be around to insure that the door is open at the proper time and closed when there is precipitation in the weather conditions.
Furthermore, the size of such an access opening is normally fixed such that the control of air therethrough can not readily be varied because the orifice size of such access opening is normally either wholly open or completely closed.
Accordingly, there is a need for a ventilating device which serves the function of a variable restriction so as to properly modulate the passage of air therethrough in order to prevent premature condensation of the moisture in the air passing through the bin. This will keep such moisture out of the grain and, as is especially important, from depositing on the upper layers of the grain.
There is also a need to have a variable restriction ventilating device which can function properly during both the drying and the storing cycles of the grain, so that doors do not need to be constantly regulated and so that separate devices are not needed for drying and storing.